Engine is 04 LLY engine with <60K on it, which I purchased new in 04. Engine/truck is all factory stock (air intake, exhaust, etc). During load conditions (e.g., acceleration, inclined roads, speeds above 65mph, etc) a moderately loud high pitched "YEEEE" noiese comes from under the hood. The noise sounds like and high pressure air leak when the turbo kicks in. The noise appears to be coming from high in the engine area, around the turbo charger. The truck does not do it any other time. Noise started after having warranty work done on the truck at Chev dealer where they replaced the alternator and a power steering hose. Alternator is not suspect as it is the second one in 1 month that they have put on it. Dealer has looked at the truck twice with no luck on what is generating the noise.

If you have a small leak at one of the intercooler pipe boots it will have a high pitched squeal.I would take them off and clean them up and reinstall them.I remember reading on here somewere that if you put hairspray on the inside of the boots they will not slip off any more.Will probably be a bit of oil inside the drivers side because of the pcv valve that sucks the oil mist into the intake tract.If I were you I would consider the pcv reroute at a minimum and also an egr blocker plate.

Here is a kit http://www.dieselplace.com/forum/showthread.php?t=240415 and i can ship an EGR plate with it.

I have interest in the fittings for the PCV kit and the EGR blocker plate. Can you provide me with info. on how to obtain by mail or phone no. to call. I'm a rookie at this type of internet chat stuff so if it here in your bio just let me know and I will go look for it.

I noticed that the PCV hose connection is not real tight on the mouthpiece and have had accumulation of oily dirt in that area. Is that coming from the PCV? What a poor design. Look forward to getting that disconnected.

Regarding the lower intercooler connections and oil there. Now I understand what’s going on with GMs poor design. When I question the dealer about the oil on the passenger side inner fender he told me it was from an engine road tube located there. Nothing to worry about. When I pulled the intercooler tube connections apart, low and behold no road tub located in that area. It was quite the mess when I pulled the intercooler coupler off down there.

Does anyone know if over tightening the coupler clamps can cause a leak?

I guess it is possible to tighten the clamps enough to bend the inter cooler or the tube ends which can cause a leak. I'm not sure how much you would have to tighten them though.

I have interest in the fittings for the PCV kit and the EGR blocker plate. Can you provide me with info. on how to obtain by mail or phone no. to call. I'm a rookie at this type of internet chat stuff so if it here in your bio just let me know and I will go look for it.

I noticed that the PCV hose connection is not real tight on the mouthpiece and have had accumulation of oily dirt in that area. Is that coming from the PCV? What a poor design. Look forward to getting that disconnected.

Regarding the lower intercooler connections and oil there. Now I understand what’s going on with GMs poor design. When I question the dealer about the oil on the passenger side inner fender he told me it was from an engine road tube located there. Nothing to worry about. When I pulled the intercooler tube connections apart, low and behold no road tub located in that area. It was quite the mess when I pulled the intercooler coupler off down there.

Does anyone know if over tightening the coupler clamps can cause a leak?Just give the girls a call at 989-479-0444.

Tighten them right down, less likely to leak.